//原始类型 按照js类型的名称来书写
let num: number = 15;
let str: string = "hello ts";
let flag: boolean = true;
let udf: undefined = undefined;
let nullType: null = null;
let syb: symbol = Symbol();
console.log("num", num);
console.log("str", str);
console.log("flag", flag);
console.log("udf", udf);
console.log("nullType", nullType);
console.log("syb", syb);
